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Pharm Test 3 > Ruminant Anesthesia > Flashcards

Ruminant Anesthesia Flashcards

1
Q

what type of anesthesia do we use with recumbency for ruminants?

A
  • Recumbency with local anesthesia/sedation - not GA
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2
Q

why is general anesthesia less common in adult ruminants?

A

1.Withdrawal times
2.Due to equipment required
3.Risks of GA without ET intubation

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3
Q

what is the ideal method of anesthesia for ruminants? why

A

Sedation & Local Anesthesia is Ideal

-less risk of complications (GI, resp, cardiovascular)
-minimal equipment required
-established withdrawl times

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4
Q

Ruminant Anesthesia Disadvantages

A

Endotracheal intubation
>required with GA
>need ET tubes and skill

Expense of equipment

<inhalational>estimated withdrawl times
</inhalational>

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5
Q

risks of ruminant anesthesia?

A

WITH UNCONSCIOUSNESS
>Ruminal Distension and Bloat
>Regurgitation & aspiration if not intubated
>Potential to develop neuropathy and myopathy with prolonged recumbency & poor positioning
>Potential development of hypoxemia

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6
Q

ruminant age considerations for anesthesia, <2 months

A

< 2 months
* Immature liver enzyme function until approx. 3 mos
* Benzodiazepines may have prolonged effect
* Prolonged recovery potential

Reversal should be available

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7
Q

cardiovascular concerns for ruminants under GA

A
  • hypotension is less - vs. equine or SA
    MBP<60 mmHg not as common unless…

> Dehydrated/sick
Neonate/pediatric age as in all other species
Hypoventilation results in higher PaCO2

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8
Q

respiratory concerns for ruminants under GA

A
  • Prone to hypoventilation (fast shallow breaths)
  • Small increase in PaCO2 acceptable
  • Will require assistance for ventilation once intubated

Hypoventilation results in higher PaCO2, which supports sympathetic tone

Hypoxemia due to:
* GI push on chest and bloat
> V/Q mismatch - Atelectasis
> Prolonged times and dorsal recumbency will promote hypoxemia

– Pulmonary Intravascular Macrophage Degranulation
* “PIMS”
* Small ruminants most typical

– Post xylazine sedation
* See rapid RR
* Poor colour – grey – blanched mucous membranes
* Hypoxemia
* Evidence of Pulmonary edema

– Reversal and support required

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9
Q

GI concerns for ruminants under GA

A

significant!
-salivation
-bloat
-regurgitation, aspiration

Withholding food and water times
-To reduce GI volume and gas producing bacteria, but will still have regurgitation and bloat

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10
Q

should we use anticholinergics to reduce salivation in ruminants under GA? why?

A

– –
Large amounts of salivation
Anticholinergics not indicated to reduce this as
* Reduction in saliva but increased viscosity
* Reduced GI motility with atropine
* Ruminants have Atropinase enzyme

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11
Q

how to position ruminants under GA to reduce salivation complications

A

occiput elevated, nose positioned down
>reduces aspiration

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12
Q

why is bloat a concen for ruminants under GA?

A

because ventilation is impeded

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13
Q

regurgitation/ aspiration becomes a higher risk for ruminants under GA if:

A

– struggling
– light at intubation
– bloat
– not off feed

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14
Q

do ruminants require an endotracheal tube for GA? why?

A
  • Mature ruminants-require endotracheal intubation with GA or full unconsciousness
    – To protect airway
    – To provide ventilatory support
  • Ruminants -moderately difficult to intubate as they mature
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15
Q

pre-anesthetic prep for ruminants

A

Physical examination +/- blood-work

Appropriate fasting times
* For the age

Organization
* People necessary and sequence of events
> Larger the animal very important
* Equipment
* Anesthetic agents

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16
Q

fasting guidelines for neonatal ruminants

A

Fasting 1-2 day old neonatal calf/sheep/goat is not generally recommended
* But ensure last bottle feed >1 hr

17
Q

fasting guidelines for ruminants 2-4 weeks old

A
  • withhold 1-2 hrs
18
Q

fasting guidelines for adult ruminants

A

– Adult Ruminants:
* Food 24 hrs; water 12-18 hrs

– Large bulls:
* Food 24-36 hrs; water 12-18 hrs

19
Q

properties of xylazine as an induction agent

A

-Excellent quality of sedation
* reliable, predictable, dose- dependent
-Reversible
-Analgesic
-Ruminants are more sensitive
* Lower dose compared to equine/SA
-Stabilization to prevent cardiorespiratory side effects
* still best option for sedation in adult
-Withdrawal Time Established
* (3 d meat/ 48 hrs milk)

20
Q

when are diazepam or midazolam used as premedicaiton in ruminants? why?

A

Not routinely used as sedative in adult bovine;
* Ataxia issue
* Minimal calming

Common choice in small ruminants, calves
* Induces moderate sedation

21
Q

when are diazepam or midazolam used as premedicaiton in ruminants? why?

A

Not routinely used as sedative in adult bovine;
* Ataxia issue
* Minimal calming

Common choice in small ruminants, calves
* Induces moderate sedation

22
Q

withdrawl times for xylazine in ruminant

A

30 days meat; not to be used in lactating animals

23
Q

what is ketamine used for in ruminants? how do we administer?

A

premedication is followed by ketamine for induction
-Surgery ≈ 10-15 min duration with xylazine premedication

24
Q

do we commonly use benzodiazepines in ruminants? why?

A

Benzodiazepines not as commonly used as long withdrawal
-Xylazine gives the muscle relaxation
-Consider the case

25
Q

if we use GG plus ketamine for induction, what should we be careful of

A

Need support for induction
* GG=guaifenesin
* Need <5% as causes hemolysis

26
Q

most common adult small ruminant induction option? what else is possible?

A
  • Ketamine is the most common
  • Propofol and Alfaxalone also possible
27
Q

if wew use propofol or alfaxalone for small ruminant induction, what do we give prior? what do we give if sick?

A

– Benzodiazepines, Butorphanol or alpha2-agonist sedation prior
– Benzodiazepine of butorphanol if sick

– Alpha2-agonist sedation on case by case basis
* Avoid if Sick animal
* Avoid if history of PIMS on farm

28
Q

induction options for a calf/lamb/kid <2 weeks old

A

Mask Inhalant possible
* Little fear of regurgitation if young (monogastric stage)

Propofol or alfaxalone

Ketamine/Benzodiazepine
* Reduced microsomal liver enzyme capacity
* Reversal for benzodiazepine

29
Q

Calf/Lamb/Kid Induction Options
> 2 weeks

A

Sedation:
* Xylazine, Diazepam/Midazolam, and or Butorphanol
* Remove alpha2-agonist if sick
Induction:
* Ketamine alone
* Diazepam + Ketamine together
* Other induction agents can be used such as Propofol or Alfaxalone
> not as commonly available to ruminant practitioner

30
Q

what is a ketamine stun and when would we use it? why?

A

Sub-anesthetic doses of ketamine
* For dehorning or castration
* With xylazine and/or butorphanol

Goal is added safety & reduced struggle for animal and practitioner
* Consider supplemental pain medication
* Some studies available – be careful to ensure “sub-anesthetic”

31
Q

why is ruminant intubation a challenge?

A

Anatomy differences:
* Poor Jaw mobility – cannot open wide
* Large fleshy Tongue – impacts view – in your way * Larynx position-caudal and sloping
* Smaller endotracheal tube than expect

– If endotracheal tube is too long – easy to intubate the right main stem bronchus

32
Q

airway anatomy of the ruminant that makes ET tube intubation a challenge

A
  • Limited jaw mobility
  • Narrow intermandibular space
  • Deeply caudal laryngeal opening
  • Thick tongue base
  • Elongated soft palate
33
Q

what should we do rapidly after intubation of the ruminant? why?

A
  • Rapidly over-inflate cuff to reduce chance of aspiration of regurgitated material
    – Small animal technique takes too long in light animal
    – After animal stable with less chance of regurgitation, inflate cuff properly if feel have overinflated cuff
34
Q

basic techniques for ruminant intubation

A

– Blind Intubation; sheep and calves, mature animal
– Direct Visualization; sheep and calves

– Palpation; mature bovine

35
Q

maintenance options for ruminant anesthesia

A

Inhalant-preferred for maintenance
* Isoflurane or Sevoflurane
* Ventilation required as prone to > hypoventilation
* MAC levels same for ruminants as in other species

Triple Drip Mixtures

Alpha2-agonist/Ketamine additional doses
* >1 month

Propofol or Alfaxalone additional doses or TIVA
* Small ruminants

36
Q

how do we monitor depth of anesthesia in ruminants?

A

Palpebral reflex maintained
* Ocular rotation classic

Muscle Tone, Movement
* Esophageal movement when light
> Reflux starting
* Shivering

Respiratory System
* RR and depth, SPO2, ETCO2, Blood gases

Cardiovascular System
* HR, ECG, BP

37
Q

considerations for ruminant recovery: positioning and reasons for it, airway, extubation?

A

Place in sternal - Examine Airway: Remove Debris

Reduce atelectasis by
* Returning to sternal / sighing (ruminant)
* Waiting for eructation

Maintain Airway until they can maintain sternal and strong swallowing reflex

Extubate with cuff partially to fully inflated

Ruminants are very calm and smart!!!

Pharm Test 3 (16 decks)

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